The present invention generally relates to electrostatic discharge protection (ESD) systems and more particularly to a system and a method for protecting an electrically-inactive component of a thermal ink jet printing system from an ESD event.
Electrostatic discharge (ESD) events are potentially serious occurrences that can cause major damage to an electronic device such as a printing system. A typical ESD event is usually a high voltage occurrence and can easily damage or destroy a printing system and particularly the printhead, which is designed to operate at small voltages.
Thermal ink jet printing systems typically contain both electrically-active (or electrical) components (such as, for example, resistors and capacitors) and electrically-inactive components (such as certain types of thin-film layers) that have a primarily non-electrical function. An ESD event to the printhead of a thermal ink jet printing system can easily damage or destroy the components contained within the printhead. Further, damage can occur not only to the electrical components of the printhead, but also to the electrically-inactive components of the printhead.
Although many printing systems contain ESD protection systems, current ESD protection schemes are designed to protect only the electrical components of the printing system. Hence, the electrically-inactive components are generally left unprotected from potentially damaging ESD events. This is a problem because, even if the electrical components have ESD protection, an ESD event still can cause damage to the electrical components of the printing system, especially if the electrically-inactive component is in close proximity to the electrical component. Therefore, there exists a need for an ESD protection system that provides protection from ESD events for not only electrical components of a thermal ink jet printing system, but also the electrically-inactive components.
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention is embodied in a system and method for protecting a thermal ink jet printing system from electrostatic discharge (ESD) by protecting electrically-inactive components of the system. By providing ESD protection to the electrically-inactive components, a more complete and efficient ESD protection system is achieved that provides an additional measure of ESD protection for the electrical components of the printing system. Electrically-inactive components are components of the printing system that have no electrical function and structures (for example, thin-film layers) that have a primarily non-electrical purpose.
The present invention provides highly effective and efficient ESD protection to printing systems containing electrically-inactive components. In particular, by providing ESD protection to the electrically-inactive components of the printing system as well as the electrical components, the present invention greatly reduces the susceptibility and sensitivity of a printing system (particularly the printhead) to damage or destruction from an ESD event. Moreover, the present invention can be implemented within a printhead of the printing system using the existing structures and circuitry of the printhead or by suitable microfabrication and thin-film techniques.
The system of the present invention includes an ESD protection system that is positioned such that an ESD event is directed away from an electrically-inactive component of a printing system. The ESD protection system of the present invention reduces the damaging effects of an ESD event and, in some embodiments, can even prevent an ESD event from occurring. The ESD protection system of the present invention includes several embodiments to accomplish this.
In particular, one embodiment of the ESD protection system provides an electrically floating large conductive area for dissipation of an ESD event. This large conductive area, which is capacitively coupled to an electrically-inactive component, reduces the sensitivity of the electrically-inactive component to an ESD event by providing a storage area for the ESD event. In another embodiment, the large conductive area and the electrically-inactive component are kept at the same potential or ground, thereby greatly reducing and even eliminating the occurrence of an ESD event. Further, in order to provide ESD protection during a manufacturing process, the embodiment can include a severable link (such as a fuse) so that the electrically-inactive component and the large conductive area are kept at the same potential for a certain period of time before the connection between the large conductive area and the potential is severed. As such, the ESD protection system greatly reduces the occurrence of an ESD event during the manufacturing process without affecting the normal operation of the printing system.
Another embodiment of the present invention includes an ESD protection system that provides a preferred breakdown location for an ESD event at a location away from any electrically-inactive components. Even if all other ESD protection systems fail, the resulting damage to the printing system will be in a location that does not affect the printing system operation. Other embodiments of the present invention include various ESD protection system that divide the large conductive area within the printing system into various thin-film layers. The charge from an ESD event is stored in these various layers thereby avoiding the creation of a high charge area in any single layer that could damage the layer. Further, a shunt bar can be used to provide a preferred path for an ESD event to follow, this preferred path being away from the electrically-inactive component. The present invention also includes a method of protecting a printing system having an electrically-inactive component using the aforementioned systems.
Other aspects and advantages of the present invention as well as a more complete understanding thereof will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. Moreover, it is intended that the scope of the invention be limited by the claims and not by the preceding summary or the following detailed description.